Evaluating of middle ear pressure changes in children undergoing circumcision operation under ketamine anesthesia

Objective: Ketamine is one of the intravenous anesthetic drugs used in painful short-term surgical procedures. In our study we aimed to evaluate the effect of intravenous ketamine on middle ear pressure in patients who are undergoing surgical circumcision. Materials and Methods: 60 patients between 3-12 years old, ASA physical status I or II and who were undergoing surgical circumcision, were studied. After arrival of patients and their parents in the waiting room, all patients were monitored ECG, noninvasive blood pressures, and peripheral oxygen saturation (SPO2) were measured (Datex-Ohmeda S/5 TM Compact Anesthesia Monitor, GE Healthcare Helsinki, Finland). Noninvasive systolic, diastolic and mean arterial pressures (SBP, DBP, MBP), heart rate (HR), and SPO2 were recorded. Left and right middle ear pressures (MEP) were determined with tympanometry and recorded as control values. In the premedication room midazolam 0,05 mg/kg iv was given and 15 minutes after premedication MEP measures with tympanometry were repeated. After arriving in the operating room, patients were monitored SBP, DBP, MBP, HR, and SPO2 were recorded. During the operation and in the recovery room oxygen support with face mask and iv fluid replacement with 1/3 isodex were provided. Anesthesia was induced with ketamine 2 mg/kg iv. After performance a dorsal penil blockade with bupivacaine 0,25% by the surgeon the operation was allowed to start. Maintanence dose of ketamine 0,5 mg/kg iv was given to patients who sensed pain during the procedure and whose heart rate and noninvasive blood pressure were 20 % increased than values measured after the first dosage of ketamine. At the 5th, 10th, 15th, 30th, 60th, 120th minutes after the first dose of ketamine left and right MEPs, HR, SBP, DBP and MBP were measured and recorded. Results: The left and right MEPs measured at the 5th,10th and 15th minutes after the first dose of ketamine were significantly higher when compared with the control values (p<0,005). Right and left MEPs measured at the beginning did not differ significantly from the values measured after the premedication with midazolam (p>0,005). Although there were no significant difference between MEP values measured at the beginning and at the 30th, 60th and 120th minutes after the ketamine dose (p>0,005). Conclusion: Ketamine caused a statistical significant increase of middle ear pressure but measured left and right mean MEPs were in normal clinical rates. When patients were examined in details, MEPs higher than normal values existed but these could not build a statistical significant mass in number. We examined the effects of higher ketamine doses on MEP values and we determined no consistence of MEP increase with extra dosage. However in our study total ketamine dose has not exceed the line of 3 mg/kg. New studies on the effects of higher ketamine doses on MEP are needed. Consequently it is estimated that ketamine which is mostly used and which has an increasing effect on MEP in children suffering from middle ear pathologies and with incompetent eustachian function, must be used conservatively. Keywards: Middle ear pressure, Ketamine, Circumcision